In the technical field called nanotechnology, application of nanometer scale fine particles (nanoparticles) in a variety of technical fields such as, for example, electronic materials, optical materials, catalysts, biotechnology, medicine, and optical crystals has attracted more attention in these several years.
Most of the conventional productions of nanoparticles, and particularly nanoparticles comprising organic polymers, are based on the method of forming fine particles by emulsifying or dispersing an appropriate polymer in an organic solvent. In this method based on dispersing of a polymer in a liquid, the shape of the fine particles in general necessarily becomes spherical, and thus non-spherical, particularly flat plate-shaped nanoparticles, that is, nanodisks, cannot be easily produced simply by dispersing a polymer in a solvent.
Flat plate-shaped nanoparticles are attracting attention mainly in the field of photographic emulsions. However, such fine particles are all flat plate-shaped particles having silver halide, particularly silver chloride, and the constituent components and the uses are limited (for example, Patent Document 1 and Patent Document 2).
Patent Document 3 also discloses a planiform plate-shaped organic filler using a thermoplastic resin and a method for producing the same. This method requires complicated processes such as repeatedly laminating a laminate in which at least two layers of a layer containing a thermoplastic resin and a layer containing a thermoplastic resin having a lower melting point compared to the former thermoplastic resin are laminated to form an ultra-multilayer laminate (Patent Document 3).
Patent Document 1: JP-A No. 2000-56419 (P2000-56419A)
Patent Document 2: JP-A No. 10-319528
Patent Document 3: JP-A No. 11-199706